7 stable releases
2.0.3 | Sep 23, 2024 |
---|---|
1.2.0 |
|
1.1.3 | Sep 13, 2024 |
1.1.2 | Feb 27, 2024 |
1.0.1 |
|
#31 in Parser tooling
1,231 downloads per month
Used in 2 crates
20KB
187 lines
descape
Provides utilities for easily parsing escape sequences in a string, using alloc::borrow::Cow
to only borrow when needed.
This library supports many escape sequences:
\\a
->\x07
\\b
->\x08
\\t
->\x09
\\n
->\x0A
\\v
->\x0B
\\f
->\x0C
\\r
->\x0D
\\e
->\x1B
\\'
->'
\\"
->"
\\`
->`
\\\\
->\\
\\xNN
->\xNN
\\o
->\o
, for all octal digitso
\\oo
->\oo
, for all octal digitso
\\ooo
->\ooo
, for all octal digitso
\\uXXXX
->\u{XXXX}
\\u{HEX}
->\u{HEX}
Along with this, you can define your own custom escape handlers! See UnescapeExt::to_unescaped_with
for more information on that.
This crate supports no-std
.
Optionally, this crate has the std
and core_error
features,
to allow the error type of an invalid escape to implement the Error
trait.
std
uses std::error::Error
, and core_error
depends on core::error::Error
, which is stable on Rust 1.82.0 or greater.
Examples
Parsing an escaped string
let escaped = "Hello,\\nworld!".to_unescaped();
assert_eq!(
escaped.unwrap(),
Cow::Owned::<'_, str>("Hello,\nworld!".to_string())
);
Not allocating for a string without escapes
let no_escapes = "No escapes here!".to_unescaped();
assert_eq!(
no_escapes.unwrap(),
Cow::Borrowed("No escapes here!")
);
Erroring for invalid escapes
// v invalid at index 7
let invalid_escape = r"Uh oh! \xJJ".to_unescaped();
assert_eq!(
invalid_escape.unwrap_err().index,
7
);
Permitting any escape, handing it back raw
fn raw(idx: usize, chr: char, _: &mut CharIndices) -> Result<Option<char>, ()> {
Ok(Some(chr))
}
let escaped = r"\H\e\l\l\o \n \W\o\r\l\d";
let unescaped = escaped.to_unescaped_with(raw).expect("this is fine");
assert_eq!(unescaped, "Hello n World");
Removing escape sequences entirely
fn raw(idx: usize, chr: char, _: &mut CharIndices) -> Result<Option<char>, ()> {
Ok(None)
}
let escaped = r"What if I want a \nnewline?";
let unescaped = escaped.to_unescaped_with(raw).expect("this should work");
assert_eq!(unescaped, "What if I want a newline?");
Not allowing escape sequences unsupported by Rust
fn rust_only(idx: usize, chr: char, iter: &mut CharIndices) -> Result<Option<char>, ()> {
match chr {
'a' | 'b' | 'v' | 'f' | 'e' | '`' => Err(()),
_ => descape::DefaultHandler.escape(idx, chr, iter)
}
}
r"This is \nfine".to_unescaped_with(rust_only).expect(r"\n is valid");
r"This is not \fine".to_unescaped_with(rust_only).expect_err(r"\f is invalid");